[all-commits] [llvm/llvm-project] def617: [BOLT] Emit empty FDE for injected functions

[Amir Ayupov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: def6174d2a7a5a66b3871d4ce5035a71e513e6ef
      https://github.com/llvm/llvm-project/commit/def6174d2a7a5a66b3871d4ce5035a71e513e6ef
  Author: Amir Ayupov <aaupov at fb.com>
  Date:   2024-04-11 (Thu, 11 Apr 2024)

  Changed paths:
    M bolt/include/bolt/Core/BinaryFunction.h
    M bolt/test/X86/patch-entries.test

  Log Message:
  -----------
  [BOLT] Emit empty FDE for injected functions

This fixes an issue where `PatchEntries` overwrites function body but
keeps CFI untouched. Existing FDEs thus become invalid. This doesn't
affect unwinding because patched functions are transparent from
EH/unwinding perspective, but it breaks BOLT during disassembling those
functions.

Emit empty FDE for injected functions (emitted to the same address as
.org functions) that take precedence over the original FDE.

This adds eh_frame overhead, but restores the ability to disassemble
.org functions. Note that the overhead is avoided in `-use-old-text`
mode.

Test Plan: updated bolt/test/X86/patch-entries.test

Reviewers: rafaelauler, maksfb, dcci, ayermolo

Reviewed By: maksfb, dcci

Pull Request: https://github.com/llvm/llvm-project/pull/87967



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